LTC1261CS#PBF Linear Technology, LTC1261CS#PBF Datasheet - Page 5

• Manufacturer Part Number: LTC1261CS#PBF
• Description: IC VOLT INVERT SW-CAP ADJ 14SOIC
• Manufacturer: Linear Technology
• Type: Switched Capacitor (Charge Pump), Invertingr

Specifications of LTC1261CS#PBF

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: -1.25 ~ -8 V
• Current - Output: 15mA
• Frequency - Switching: 550kHz
• Voltage - Input: 3 ~ 8 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 14-SOIC (3.9mm Width), 14-SOL
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -

PIN
Pin numbers are shown as (LTC1261CS/LTC1261CS8).
NC (Pin 1/NA): No Internal Connection.
C1
capacitor between C1
doubler mode, connect a 0.1 F capacitor from C1
C2
C1
capacitor from C1
doubler mode only, C1
C2
nect a 0.1 F capacitor from C2
with the LTC1261CS in tripler mode only; in doubler
mode this pin should float.
C2
connect a 0.1 F capacitor from C2
mode connect a 0.1 F capacitor from C1
GND (Pin 6/Pin 4): Ground. Connect to a low impedance
ground. A ground plane will help to minimize regulation
errors.
R0 (Pin 7/NA): Internal Resistor String, 1st Tap. See
Table 2 in the Applications Information section for infor-
mation on internal resistor string pin connections vs
output voltage.
R1 (Pin 8/NA): Internal Resistor String, 2nd Tap.
R
nect this pin to ADJ to use the internal resistor divider.
See Table 2 in the Applications Information section for
information on internal resistor string pin connections vs
output voltage.
ADJ (COMP for fixed versions) (Pin 10/Pin 5): Output
Adjust/Compensation Pin. For adjustable parts this pin is
used to set the output voltage. The output voltage should
be divided down with a resistor divider and fed back to
this pin to set the regulated output voltage. The resistor
divider can be external or the internal divider string can
ADJ
+
–
–
+
–
U
.
(Pin 2/ Pin 2): C1 Positive Input. Connect a 0.1 F
(Pin 3/Pin 3): C1 Negative Input. Connect a 0.1 F
(Pin 4/NA): C2 Positive Input. In tripler mode con-
(Pin 5/NA): C2 Negative Input. In tripler mode
(Pin 9/NA): Internal Resistor String Output. Con-
FUNCTIONS
U
+
U
+
to C1
–
and C1
should float.
–
. With the LTC1261CS in
–
+
. With the LTC1261CS in
to C2
+
to C2
–
. This pin is used
+
–
to C2
. In doubler
–
.
+
to
be used if it can provide the required output voltage.
Typically the resistor string should draw 10 A from the
output to minimize errors due to the bias current at the
adjust pin. Fixed output parts have the internal resistor
string connected to this pin inside the package. The pin
can be used to trim the output voltage if desired. It can
also be used as an optional feedback compensation pin
to reduce output ripple on both adjustable and fixed
output voltage parts. See Applications Information sec-
tion for more information on compensation and output
ripple.
OUT (Pin 11/Pin 6): Negative Voltage Output. This pin
must be bypassed to ground with a 1 F or larger capaci-
tor; it must be at least 3.3 F to provide specified output
ripple. The size of the output capacitor has a strong effect
on output ripple. See the Applications Information sec-
tion for more details.
REG (Pin 12/Pin 7): This is an open drain output that pulls
low when the output voltage is within 5% of the set value.
It will sink 8mA to ground with a 5V supply. The external
circuitry must provide a pull-up or REG will not swing
high. The voltage at REG may exceed V
pulled up to 12V above ground without damage.
SHDN (Pin 13/Pin 8): Shutdown. When this pin is at
ground the LTC1261 operates normally. An internal 5 A
pull-down keeps SHDN low if it is left floating. When
SHDN is pulled high, the LTC1261 enters shutdown
mode. In shutdown the charge pump stops, the output
collapses to 0V and the quiescent current drops to 5 A
typically.
V
voltage between 3V and 6.5V. Certain combinations of
output voltage and operating mode may place additional
restrictions on the input voltage. V
to ground with at least a 0.1 F capacitor placed in close
proximity to the chip. See the Applications Information
section for details.
CC
(Pin 14/Pin 1): Power Supply. This requires an input
CC
must be bypassed
LTC1261
CC
and can be
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